Ok I'm studying for the instrument written and I came across this question and the answer/explanation in the book is bugging me. Here's the question I thought the altimeter would read LOWER than normal but according to the book the correct answer is C, with the explanation that "the pressure within an unpressurized cockpit is slightly lower than the pressure outside the airplane because of the Venturi efffect...." Now, that explanation makes perfect sense to me except that I thought the air pressure in my cabin was HIGHER than the outside air pressure. I think this because in my plane (Archer II) I have a small "storm" window on the pilot side that opens inward. In flight this window is very difficult to open because(I thought) positive pressure in the cabin was pushing and holding it closed(outward). I had always assumed this was because of air being rammed in through the fresh air vents on the wing leading edges and tail creating a slightly higher pressure. What I can't figure out is why, if the book is right and cabin air pressure is in fact lower why my storm window wouldn't in fact fly open when I undo the latch rather than needing to be pried open with fingernails. Can someone explain where my logic or perhaps the book explanation has failed me?